Modulating Decarboxylative Oxidation Photocatalysis by Ligand Engineering of Atomically Precise Copper Nanoclusters.

Copper nanoclusters (Cu NCs) characterized by their well-defined electronic and optical properties are an ideal platform for organic photocatalysis and exploring atomic-level behaviors. However, their potential as greener, efficient catalysts for challenging reactions like decarboxylative oxygenation under mild conditions remains unexplored. Herein, we present Cu(Nap)(PPh)H (hereafter CuNap), protected by 1-naphthalene thiolate (Nap), which performs well in decarboxylative oxidation (90% yield) under photochemical conditions. In comparison, the isostructural Cu(DCBT)(PPh)H (hereafter CuDCBT), stabilized by 2,4-dichlorobenzenethiolate (DCBT), yields only 28%, and other previously reported Cu NCs (Cu, Cu, Cu, Cu, and Cu) yield in the range of 6-18%. The introduction of naphthalene thiolate to the surface of Cu NCs influences their electronic structure and charge transfer in the ligand shell, enhancing visible light absorption and catalytic performance. Density functional theory (DFT) and experimental evidence suggest that the reaction proceeds primarily through an energy transfer mechanism. The energy transfer pathway is uncommon in the context of previous reports for decarboxylative oxidation reactions. Our findings suggest that strategically manipulating ligands holds significant potential for creating composite active sites on atomically precise copper NCs, resulting in enhanced catalytic efficacy and selectivity across various challenging reactions.